Device for producing high pressure in a fluid in miniature

ABSTRACT

A miniaturised device for producing high pressure in a fluid imposes stringent requirements on the manufacturing process.  
     The device according to the invention consists of a hollow piston displaceably mounted in a cylinder and a valve member which is guided by the hollow piston and mounted so as to be axially movable relative to the hollow piston. The valve member is arranged at one end of the hollow piston inside or immediately in front of the end of the hollow piston.  
     The device is used in a mechanically operated high pressure atomiser. This consists of a two part housing which comprises a pump housing with nozzle, a blocking mechanism, a spring housing with spring, a non-pressurised storage container for the fluid and a mechanical counter integrated in the spring housing.  
     The valve operates without any auxiliary force, closes very rapidly and is sealed tight against high pressure. The atomiser is safe and simple to operate and environmentally friendly. The fluid is metered extremely accurately.  
     The atomiser is used, for example, to produce an inhalable aerosol of a liquid medicament without the use of propellant gas, at 320 bar, for example.

[0001] The invention relates to a device for producing high pressure ina fluid. It comprises a piston which is movable in a cylinder, and avalve, both preferably of miniaturised construction. The inventionfurther relates to a high pressure atomiser which contains this device,and the use thereof, preferably for medicinal purposes.

[0002] One aim of the invention is to enable a device of this kind andthe atomiser containing the device to be made simpler in design andcheaper to produce and suited to its function.

[0003] In liquid chromatography (HPLC), for example, generallyrelatively small quantities of liquid are conveyed at high pressurethrough the separating column. Moreover, in medicinal aerosol therapy,aerosols are obtained, by atomising or nebulising liquid drugs fortreating diseases of the respiratory tract in humans or for treatingasthmatic conditions. Here again, a high pressure is required in a,generally relatively small, quantity of fluid in order to produce thesmall droplet size needed for the aerosol. In the metered dose inhaleraccording to U.S. Pat. No. 5,497,944, (the entire contents of which areincorporated herein by reference) a predetermined volume of a fluid issprayed through a nozzle with a small aperture under a pressure ofbetween 5 and 40 MPa (about 50 to 400 bar) to produce an aerosol. Thepresent invention is particularly applicable to such metered doseinhalers and similar devices.

[0004] According to one aspect of the invention there is provided adevice, preferably of miniaturised construction, for producing highpressure in a fluid, comprising a piston which is movable in a cylinder,a high pressure chamber which is located in front of the piston insidethe cylinder, and a valve, which device includes

[0005] a cylindrical hollow piston,

[0006] a valve member which is guided by the hollow piston and ismounted so as to be axially movable against the hollow piston,

[0007] a stop means on the hollow piston which holds the valve member tothe hollow piston and

[0008] a defined (predetermined) sealing surface at the inlet end of thevalve member, the valve member generally being restrained from rotationabout any axis transverse to the piston axis.

[0009] According to another aspect of the invention, there is provided adevice for producing high pressure in a fluid, preferably ofminiaturised construction, comprising a cylinder, a hollow cylindricalpiston which is movable in the cylinder and provides a path for fluidtherethrough, a high pressure chamber which is located in front of thepiston inside the cylinder and which is supplied with fluid through saidpath, and an inlet valve in said fluid path which moves with the pistonbut is also capable of limited guided movement along the piston axisbetween a closed position in contact with a valve seat provided by thepiston and an open position spaced from the valve seat, the valve memberbeing so shaped and guided that it cannot rotate about any axistransverse to the piston axis such that a predetermined surface thereofengages the seat.

[0010] In U.S. Pat. No. 5,497,944, there is described and shown asimilar device in which the check valve member is a ball. With such anarrangement, the ball can rotate during multiple operations. It has beenfound that wear and distortion under the high pressure involved canpermanently deform the ball so that if a different part of its surfaceis used during sequential closing and sealing operations (because theball is free to rotate about a transverse axis) there is a tendency forleakage to occur. This can be avoided by using the same surface of thevalve member each time thus allowing bedding down to ensure the desiredseal. In the preferred arrangement according to the invention, at leasta major part of the valve member is cylindrical and is guided in achamber (which may, for example, be the pump chamber itself or may bepart of the interior of the piston) and the valve member cylinder has anend surface which co-operates with the valve seal provided by thepiston. Another disadvantage of a ball valve which can be avoided usingthe invention is that that traverse area of the valve is necessarilyconsiderably smaller than the diameter of the ball and thus the guidecylinder in which it moves; this leads to a reduction in the foreapplied by the valve member to the valve seat arising from fluidpressure generated during the pressure stroke (forward movement) of thepiston. A high application force of the valve member is desirable toslightly elastically deform the valve member and and/or the valve seatto close any slight gaps between them.

[0011] In the specification which follows, the terms inlet and outletside or inlet and outlet end are used in relation to the main directionof flow of the fluid within the device. The term fluid includes bothgases and liquids but the present invention is mainly concerned withliquids.

[0012] The valve member is somewhat displacable against the hollowpiston but it moves substantially with the hollow piston.

[0013] The valve member is preferably uniaxially rotationallysymmetrical in shape, e.g. it is a circular cylinder or a frusturn. Itscross-section is somewhat smaller than the cross-section of the chamberin which the valve member is movably mounted. This is achieved by meansof one or more channels preferably extending in the outer surface of thecylindrical valve member, or by a somewhat smaller diameter of the valvemember in relation to the diameter of the chamber in which the valvemember is movably mounted.

[0014] The valve member is guided in the chamber in which it is movablymounted; a cylindrical valve member can rotate about its axis asrequired, but its axis always remains parallel to the axis of the hollowpiston. This produces a defined sealing surface at the inlet end of thevalve member.

[0015] The distance over which the valve member can travel relative tothe hollow piston is limited by a stop or stop means which holds themovable valve member together with the hollow piston.

[0016] In some embodiments of the invention wherein the stop is beyondthe outlet end of the valve member, there may need to be at least onerecess in the region of the outlet end of the valve member to enable thefluid to flow through between the stop and the valve member when thevalve is open. The or each recess is located either in the valve memberat the outlet end thereof or in the stop in the hollow piston.

[0017] In the position where the valve member abuts on the stop of thehollow piston, the valve is opened. In the position where the valvemember abuts on the defined sealing surface, the valve is closed.

[0018] A valve member arranged inside the hollow piston has virtually nofriction against the inner wall of the hollow piston. A valve memberarranged directly in front of the end of the hollow piston may possiblyrub against the wall of the main pump cylinder of the device. In thiscase, the valve is actively closed and opened as the hollow pistonmoves, on account of the friction between the valve member and thecylinder wall.

[0019] The cylinder preferably consists of plastics and the hollowpiston of metal or plastics. The material for the valve member isselected, in terms of its hardness, to complement the hardness of thematerial for the hollow piston and may be metal, ceramics, glass,gemstone, plastics or elastomer. The valve member is preferablymanufactured in one piece.

[0020] When the fluid is sucked in, the high pressure chamber isconnected to the fluid supply by means of the hollow piston. During theintake stroke of the hollow piston the fluid flows through the hollowpiston and past the valve member into the high pressure chamber of thecylinder. During the exhaust stroke of the hollow piston the vale seatis sealed in high pressure tight manner against the define sealingsurface of the valve member.

[0021] The device according to the invention for producing high pressurein a fluid is connected to the fluid supply at its inlet end. The highpressure chamber is connected to another device into which or throughwhich the fluid is conveyed under high pressure. The hollow piston orthe cylinder is attached to a drive which brings about relative movementbetween the hollow piston and cylinder and which applies the forcerequired to generate the high pressure.

[0022] In the first embodiment, the cylindrical valve member may beguided and mounted in axially movable manner directly in front of theend of the hollow piston, the diameter of the valve member beingsubstantially equal to the internal diameter of the cylinder. On theoutside, near its outlet end, the hollow piston has an encircling,preferably turned or shaped groove as a stop member, into which aplurality of snap hooks on the valve member engage. Instead of thegroove, the hollow piston may have at its outlet end a shaped taper withau encircling, outwardly funnel-shaped edge. The outer diameter of thehollow piston at its outlet end is greater than the base diameter of thegroove and less than the diameter of the cylinder. Instead of theencircling groove, the outlet end of the hollow piston may be providedon the outside, at several, preferably 2 diametrically opposed points,with flattened areas which form a step to act as a stop means. The flatend of the hollow piston provides a valve seat cooperating with adefined flat sealing surface on the inlet side of the valve member. Theouter edge at the end of the hollow piston may be chamfered.

[0023] In the second embodiment, the cylindrical valve member may beguided and movably mounted directly in front of the end of the hollowpiston, the diameter of the valve member being substantially equal tothe internal diameter of the cylinder. The end of the hollow piston isshaped inwardly to provide an inturned lip and acts as a stop means. Onthe valve member is mounted a coaxial, undercut, mushroom-shaped peg thesnap hooks of which engage behind the shaped edge of the hollow piston.The defined sealing surface which extends around the peg rests on theoutlet end of the piston on the edge of the lip.

[0024] In the third embodiment, the preferably cylindrical valve membermay be mounted so as to be fully movable inside the hollow piston. Theoutlet end of the hollow piston has an internal diameter greater thanthe internal diameter of the remainder of the hollow piston. The lengthof this widened portion of the hollow piston is somewhat grater than thelength of the valve member. The diameter of the valve member issubstantially equal to the inner diameter at the widened end of thehollow piston. The outlet end of the hollow piston is shaped inwardly toform a lip either over its entire periphery or over a part of itsperiphery and acts as a stop which holds the valve member inside thehollow piston. The base of the widened portion which forms the valveseat may be flat or conical. A fluid flow recess in the outlet side thevalve member may, for example, take the form of a stepped channel. Afluid flow recess in the stop may be constructed, for example, as anindentation in the lip edge.

[0025] In a variant of this embodiment, the valve member may be arrangedtotally inside the hollow piston at the inlet end thereof. The stop willthen be located at the outlet end of the widened portion and the definedsealing surface will then be on the shaped edge at the inlet end of thehollow piston.

[0026] In the fourth embodiment, the hollow piston consists of athin-walled tube which is shaped at its end projecting into the cylinderand is provided with an encircling constriction at the end of the spaceallowed for the valve member. The cylindrical valve member is guided andmovably mounted in the space between the shaped edge and the encirclingconstriction. Another thick-walled tube may be pushed into the inlet endof the hollow piston, its outer diameter being equal to the innerdiameter of the hollow piston, and this thick-walled tube further beingfixedly connected to the hollow piston and preferably extendingapproximately up to the encircling constriction in the hollow piston.The thick-walled tube acts as a displacement member and makes it easierfor the fluid to be sucked into the high pressure chamber virtuallywithout pressure being applied. The thick-walled tube is preferably madeof plastics.

[0027] In a variant of this embodiment, the valve member may be mountedfully inside the hollow piston at the inlet end thereof. The stop isthen located at the encircling constriction and the defined sealingsurface is located at the shaped edge at the inlet end of the hollowpiston.

[0028] In the fifth embodiment, the hollow piston comprises athin-walled tube which contains a thick-walled tube the outer diameterof which is equal to the inner diameter of the hollow piston, and whichis fixedly connected to the hollow piston. The thick-walled tubefunctions as a displacement body and makes it easier for the fluid to besucked in virtually without pressure being applied.

[0029] The inlet end of the hollow piston is widened. At the widenedend, the hollow piston is fixedly connected to a closure member theouter diameter of which is greater than the outer diameter of thewidened inlet end of the hollow piston. The closure member contains adepression which is open on its side facing the widened end of thehollow piston. In the base of the depression is an opening acting as aninlet for the fluid. The base of the depression may be conical or flat;it forms the defined sealing surface.

[0030] The valve member is arranged in the depression in the closuremember: it is guided so as to be axially movable in the depression. Theexternal diameter of the valve member is smaller than the internaldiameter of the depression, but preferably greater than the internaldiameter of the hollow piston in that part of it which projects into thecylinder. The valve member may contain, at its outlet end, at least onerecess through which the fluid flows into the high pressure chamberduring the intake stroke of the hollow piston.

[0031] The stop for the valve member is preferably the end of thedisplacement body which projects into the widened portion of the hollowpiston, or—if the end of the displacement body is located in theunwidened portion of the hollow piston—the transition from the unwidenedportion of the hollow piston into the widened inlet end thereof.

[0032] The hollow piston with the widened inlet end preferably consistsof meal. The displacement body and closure member are preferably made ofplastics. The valve member may be made of plastics or metal.

[0033] Of particular significance is the use of the device according tothe invention for producing high pressure in a fluid in an atomiser(nebulizer) for propellant-free spaying of the fluid.

[0034] According to another aspect of the invention, there is providedan atomiser for spraying a fluid, consisting of an upper housing part, apump housing, a nozzle, a blocking mechanism, a spring housing, a springand a supply container, characterised by

[0035] a pump housing fixed in the upper housing part which has at oneend a nozzle member with the nozzle,

[0036] a hollow piston with valve member,

[0037] a drive flange in which the hollow piston is secured and which islocated in the upper housing part,

[0038] a blocking mechanism located in the upper housing part,

[0039] a spring housing with the spring located therein, which isrotatably mounted by means of a rotary bearing on the upper housingpart,

[0040] a lower housing part which is fitted onto the spring housing inthe axial direction.

[0041] Other aspects of the invention are set out in the independentclaims but variations and combinations of particular features thereincan be made without departing from the scope of the invention. Certainpreferred features are defined in the subclaims

[0042] Further preferred features of the atomiser will now be described.The atomiser is preferably a metered dose inhaler.

[0043] The hollow piston with valve member preferably corresponds to oneof the devices according to the invention mentioned hereinbefore. Itprojects partially into the cylinder of the pump housing and is mountedin axially movable manner in the cylinder. The hollow piston with valvemember exerts a pressure of 5 to 60 MPa (about 50 to 600 bar),preferably 10 to 60 MPa (about 100 to 600 bar) on the fluid at its highpressure end at the moment of release of the spring.

[0044] The nozzle in the nozzle member is preferably microstructured,ie. produced by microtechnology. Microstructured nozzle members aredisclosed, for example, in U.S. Pat. No. 5,472,143, the entire contentsof which are incorporated herein by reference.

[0045] The nozzle member consists, for example, of two plates of glassand/or silicon firmly joined together, of which at least one plate hasone or more microstructured channels which connect the nozzle inlet endto the nozzle outlet end. At the nozzle outlet end is at least onecircular or non-circular opening less than or equal to 10 μm in size.Size in this connection refers to hydraulic diameter. Hydraulic diameterin this type of apparatus are generally less than 100 micrometrespreferably 1-20 micrometres.

[0046] The directions of spraying of the nozzles in the nozzle membermay run parallel to one another or may be inclined relative to oneanother. In a nozzle member having at least two nozzle openings at theoutlet end, the directions of spray may be inclined relative to oneanother at an angle from 20 to 160°, preferably at an angle from 60 to150°. The directions of spraying meet in the vicinity of the nozzleopenings.

[0047] In the pump housing, a non-return valve with or without springbias may be provided between the nozzle opening and the high pressurechamber of the cylinder. This non-return valve closes off the highpressure chamber in the resting state of the atomiser, protects thefluid from the entrance of air and may if necessary prevent volatilecomponents of the fluid from evaporating out of the pump housing. Thenon-return valve opens automatically as soon as the pressure of thefluid in the high pressure chamber exceeds a minimum value and thecurrent of fluid is created; it closes automatically as soon as thecurrent of fluid is exhausted. The non-return valve may be, for example,a ball valve. It may also consist of a flexible plate which is clampedon one side and rests like a flap on the outlet end of the high pressurechamber. In another embodiment it may consist of a disk of preferablyflexible material, clamped all the way round, pierced by a pin. Thepierced hole allows the current of fluid to pass through to the nozzleas soon as the pressure in the fluid exceeds a minimum value. After thecurrent of fluid is exhausted, the pin hole closes up again.

[0048] The valve member is preferably mounted at the end of the cylinderfacing the nozzle member.

[0049] The blocking or latching mechanism has a spring, preferably acylindrical helical compression spring, as a store for mechanicalenergy. The spring acts on the driven flange as a jumping member themovement of which is determined by the position of a blocking member.The path of travel of the driven flange is precisely defined by an upperand lower stop. The spring is preferably tensioned by an eternal torquevia a force stepping-up device, eg. a helical sawtooth thrust cam, theforce being generated as the upper housing part rotates counter to thespring housing in the lower housing part. In this case, the upperhousing part and the driven flange comprise a single or multiplesawtooth wedge arrangement.

[0050] Mechanisms of this general type are disclosed in U.S. Pat. No.4,260,082 and GB Application 2291135 the entire contents of both ofwhich are incorporated herein by reference.

[0051] The blocking member with engaging blocking surfaces is arrangedin an annular configuration around the driven flange. It consists, forexample, of a plastics or metal ring which in one form is inherentlyradially resiliently deformable. The ring is arranged in a plane atright angles to the atomiser axis. After the biassing of the spring, theblocking surfaces of the blocking member move into the path of thedriven flange and prevent the spring from being released. The blockingmember is actuated by a button. The actuating button is connected orcoupled to the blocking member. In order to actuate the blockingmechanism the actuating button is pushed parallel to the plane of thering, preferably into the atomiser; the deformable ring is therebydeformed in the plane of the ring to release the flange for movement bythe spring.

[0052] The preferred blocking member and spring are described and shownin German Patent Application 195452267 and filed by Microparts butassigned to Boehringer Ingelheim International GmbH. The entire contentsof this application is incorporated herein by reference.

[0053] The atomiser optionally contains a mechanical counter comprisinga screw threaded spindle which is mounted on the spring housing. Theaxis of the spindle extends in the region of the outer surface parallelto the axis of the atomiser. The spindle is mounted, in the region ofits ends, by means of a rotary bearing on the spring housing. Thespindle has teeth at the end closest to the upper housing part. On theedge of the upper housing part is at least one cam which engages in theteeth at the end of the spindle when the two housing parts are rotatedrelative to one another. A slider with rotation prevention means ismounted on the spindle and engages its threads.

[0054] The preferred counter is described and shown in German PatentApplication 195 49 033.9 dated Dec. 28, 1995 and filed by Microparts butassigned to Boehringer Ingelheim International GmbH. The entire contentsof this application is incorporated herein by reference.

[0055] The lower housing part is pushed axially over the spring housingand covers the mounting, the drive of the spindle and the storagecontainer for the fluid. The position of the slider is visible through arecess in the lower housing part and can be read off on a scale, eg. onthe lower housing part.

[0056] When the atomiser is actuated the upper housing part is rotatedrelative to the lower housing part, the lower housing part carrying thespring housing with it. The spring meanwhile is compressed and biassedby means of the helical thrust cam, and the blocking mechanism engagesautomatically. The angle of rotation is preferably a whole-numberfraction of 360°, eg. 180°. At the same time as the spring is biassed,the driven part in the upper housing part is moved a certain distance,the hollow piston is retracted inside the cylinder in the pump housing,as a result of which some of the fluid is sucked out of the storagecontainer into the high pressure chamber in front of the nozzle.

[0057] By means of the gears, which consist of a piston on one end ofthe spindle and a rack or racks on the edge of the upper housing part,the relative movement of the two housing parts is picked up andconverted into a rotary movement of the spindle and displacement of theslider on the spindle. On each actuation of the atomiser, the slider ismoved a certain distance along the spindle.

[0058] The position of the slider indicates what proportion of the fluidto be atomised has already been taken from the storage container and howmuch is still available. The slider on the spindle can be reset ifnecessary by means of a resetting lug.

[0059] If desired, a plurality of (preferably collapsible) replaceablestorage containers holding the fluid which is to be atomised can beinserted into the atomiser one after another and used. The storagecontainer is not pressurised or substantially not pressurised. Thepressure of the fluid in the storage container is in any casesubstantially lower than the pressure generated in the high pressurechamber by the mechanically operated atomiser. The storage containercontains, for example, a fluid containing a drug.

[0060] A suitable container with a dimensionally stable outer part andan inner part collapsible as the liquid therein is removed as disclosedin U.S. Pat. No. 5,316,135, the entire contents of which areincorporated herein by reference.

[0061] The atomising process is started by gently pressing the actuatingbutton. The blocking mechanism then opens up a path for the driven partto move. The biassed spring pushes the piston into the cylinder of thepump housing. The fluid leaves the nozzle of the atomiser in spray form.

[0062] The components of the atomiser are made of a material which issuitable for the function. The housing of the atomiser and, insofar asfunction allows, other parts are preferably made of plastics, eg. byinjection moulding. For medicinal purposes, physiologically acceptablematerials are used.

[0063] The atomiser according to the invention is used, for example, forpropellant-free production of medicinal aerosols. An inhalable aerosolwith a mass average particle (droplet) size of about 5 μm can beproduced thereby. These small particles (average size less than 12 μm)are necessary for penetration right down into the lungs. The amountdischarged is preferably about 15 microlitres.

[0064] The following active substances are mentioned by way of exampleof pharmaceutical compositions in the form of aqueous or ethanolicsolutions, depending on the solubility of the active substance: berotec,berodual, flunisolide, atrovent, salbutamol, budesonide, combivent,tiotropium, oxivent and suitable peptides.

[0065] The solutions may also contain pharmaceutically acceptableexcipients.

[0066] The preferred device according to the invention for producinghigh pressure in a fluid and the preferred atomiser containing thisdevice have the following advantages:

[0067] The device contains a valve which operates without any auxiliaryforce (produced by a spring) and closes as a result of the flowresistance of the fluid on the valve member or as a result of thefriction on the cylinder wall.

[0068] The valve is tight against a pressure generally above 3 MPa (30bar).

[0069] The valve member is made in one piece; it is easy to manufactureand assemble.

[0070] The valve closes very rapidly owing to the short distancetravelled by the valve member to reach the defined sealing surface.

[0071] The valve has a high sealing action.

[0072] As a result of the guiding of the uniaxially rotationallysymmetrical valve member, a defined sealing surface is produced which ishigh pressure tight through a very large number of cycles of movement ofthe hollow piston.

[0073] The dead space of the high pressure chamber can be kept extremelysmall.

[0074] The atomiser can be operated safely and easily even by untrainedpersons, both to bias the spring and to actuate the atomising process.

[0075] The atomiser works without propellant gas and is thereforeenvironmentally friendly.

[0076] The storage container for the fluid is not pressurised orsubstantially not pressurised.

[0077] The movement of the blocking member is automatically coupled, bya simple method, to the rotary movement for biassing the spring.

[0078] In a preferred embodiment the atomiser consists of low-wearpurely mechanical components and operates reliably over long periods.

[0079] Owing to the defined abutments for the driven part the meteringof the fluid is very accurate.

[0080] The atomiser can be manufactured cheaply and assembled easily.

[0081] The mechanical counter is automatically advanced as the atomiseris actuated; it is uncritical of tolerance, easy to assemble andoperates safely and reliably.

[0082] The counter is inaccessible when the atomiser is used properlyand cannot be falsified by accident.

[0083] The counter can be adapted to any number of releases of fluidfrom the storage container and to different overall numbers of storagecontainers to be used with one atomiser.

[0084] The counter is integrated in the atomiser and does not take upany additional space.

[0085] No substances can pass from the counter into the substance whichis to be atomised.

[0086] Preferred embodiments of the invention will now be described byway of example with reference to the drawings in which:

[0087] FIGS 1 a, 1 b and 1 c are respectively a longitudinal section ofa first embodiment of a pump for producing high pressure in a fluidaccording to the invention, an oblique view of its hollow piston and anoblique view of its valve member;

[0088]FIGS. 2a, 2 b and 2 c are similar views of a second embodiment;

[0089]FIGS. 3a, 3 b and 3 c are similar views of a third embodiment;

[0090]FIGS. 4a, 4 b and 4 c are similar views of a fourth embodiment;

[0091]FIGS. 4d, 4 e an 4 f are similar views of a modification of thefourth embodiment;

[0092]FIG. 5 is a longitudinal section of a fifth embodiment; and

[0093]FIGS. 6a and 6 b are longitudinal cross-sections of a metered doseinhaler according to the invention in different operative conditions.

[0094] The various embodiments of the pump device have already beendescribed above in general terms but these descriptions will now besupplemented with further description with reference to the drawings.

[0095]FIG. 1a shows a longitudinal section, viewed obliquely, throughthe first embodiment of the device according to the invention forproducing high pressure in a fluid. In the cylinder (1) is the hollowpiston (2) with the coaxial bore (7) and the valve member (3) in thepartly open position of the valve. Between the bottom of the valvemember (3) and the end of the cylinder is the high pressure chamber (4).The high pressure chamber is closed off by another component (notshown). Mounted on the hollow piston, outside the cylinder, is a device(not shown) by means of which the hollow piston can be displaced insidethe cylinder.

[0096]FIG. 1b shows the hollow piston (2) viewed obliquely. The end ofthe hollow piston facing the valve member is provided with a groove (5)which is bounded, at its end facing the valve member, by a rectangularsection annular land forming a step (8) the diameter of which is lessthan the external diameter of the hollow piston (2) and greater than thebase diameter of the groove. The front edge at the end of the hollowpiston may be chamfered.

[0097]FIG. 1c shows the valve member (3) viewed obliquely. It has, forexample, three channels (9) on its outer surface to facilitate fluidflow when the valve is open. Mounted on the valve member (3), on itsside facing the hollow piston, are, for example, three snap hooks (6)the width of which, in the direction of the circumference of the valvemember, is less than a third of this circumference. The snap hooks (6)are shorter in the axial direction than the length of the, for example,grooved end of the hollow piston.

[0098] During assembly, the valve member (3) is placed on the end of thehollow piston (2), and the hooks (10) slide into the groove. The hollowpiston together with the valve member is then pushed into the cylinder.

[0099] When the valve is open, the inner edge of the hooks (10) abut onthe step (8). When the valve is closed, the base of the valve member (3)facing the hollow piston fits tightly on the end of the hollow piston(2) which acts as the defined sealing surface.

[0100] In order to take in the fluid, the hollow piston is lifted partlyout of the cylinder, whereupon the valve automatically opens. The fluidflows through the bore (7) in the hollow piston and past the valvemember into the high pressure chamber (4). In order to expel the fluid,the hollow piston (2) is pushed into the cylinder (1), whereupon thevalve closes automatically, virtually instantly, and high pressure isgenerated in the fluid.

[0101]FIG. 2a shows the second embodiment of the device according to theinvention for producing high pressure in a fluid as a longitudinalsection viewed obliquely. In the cylinder (1) is the hollow piston (11)and the valve member (13) in the partly open position of the valve.

[0102]FIG. 2b shows a longitudinal section through the hollow piston(11) with the shaped outlet end (12) of the hollow piston. Adisplacement body (26) may be fixedly located in the hollow piston.

[0103]FIG. 2c shows the valve member (13) as a longitudinal sectionviewed obliquely. Mounted on the valve member is a coaxial, undercut peg(14) the projecting end of which engages behind the shaped edge (12) ofthe hollow piston. The end (15) of the peg facing the hollow piston maybe chamfered. The peg may have an indentation or bore (16) extending inthe axial direction and possibly longitudinal slots extending upwardsfrom the end (15) thus forming snap hooks so that the peg can be pushedinto the shaped end of the hollow piston, thereby engaging behind theshaped edge.

[0104]FIG. 3a shows the third embodiment of the device according to theinvention for producing high pressure in a fluid in longitudinal sectionviewed obliquely. In the cylinder (1) is the hollow piston (17) and thevalve member (18) in the closed position of the valve.

[0105]FIG. 3b shows a longitudinal section viewed obliquely through thehollow piston (17) with the shaped end (19). At the outlet end of thehollow piston is the widened portion (20) in which the valve member (18)is guided and mounted in axially movable manner. The inlet end of thewidened portion (20) is chamfered or flat.

[0106]FIG. 3c shows the cylindrical valve member (18) in longitudinalsection viewed obliquely. Both ends of the valve member are planar andare located perpendicularly to the axis of the valve member. The valvemember (18) contains, for example, four stepped channels or flats (21)on its outer surface to facilitate fluid flow past the shaped end (19),i.e. the inturned lip, when the valve is open, the ends of the channels(21) being radially inward of the lip. The edge of the valve member (18)which abuts on the inclined base of the hollow chamber (20) may bechamfered.

[0107] The diameter of the valve member (18) is less than the diameterof the widened portion (20) so that the valve member (18) can movevirtually without friction in the widened portion (20).

[0108] For assembly, the valve member (18) is pushed into the widenedportion (20) before the outlet end (19) of the hollow piston is shaped.

[0109]FIG. 4a shows the fourth embodiment of the device according to theinvention for producing high pressure in a fluid in longitudinal sectionviewed obliquely. In the cylinder (1) are the hollow piston (22) and thevalve member (23) in the closed position of the valve. The diameter ofthe valve member is less to the inner diameter of the hollow piston.

[0110]FIG. 4b shows a longitudinal section, viewed obliquely, throughthe hollow piston (22) with the shaped outlet end (24) forming aninturned lip and the encircling constriction (25). The thick-walled tube(26) acting as the displacement body may be pushed into the hollowpiston (22) and secured therein.

[0111]FIG. 4c shows the valve member (23) in oblique view. At the outletend of the valve member is a radially extending indentation (27) in theform of a transverse slot to facilitate fluid flow when the valve isopen.

[0112]FIG. 4d shows an alternative to the fourth embodiment inlongitudinal section, viewed obliquely. In the cylinder (1) is thehollow piston (28), optionally with the displacement body (26), with thevalve in the closed position. The diameter of the valve member (29) isless than the internal diameter of the hollow piston.

[0113]FIG. 4e shows a longitudinal section, viewed obliquely, throughthe hollow piston (28) with the shaped outlet end (24) and theencircling constriction (25). At least one indentation (30) in the formof a recess or notch is provided on the shaped outlet end (24) tofacilitate fluid flow when the valve is open. Instead of the indentationthere may be a convexity.

[0114]FIG. 4f shows the valve member (29) in oblique view. In this case,the valve member is a straight cylinder with no recesses.

[0115]FIG. 5 shows the fifth embodiment of the device according to theinvention for producing high pressure in a fluid, in longitudinalsection and viewed obliquely. In the cylinder (1) is the hollow piston(31) which contains the displacement body (32). Mounted on thecylindrically widened inlet end (33) of the hollow piston is the closuremember (34) with the depression (35) and bore (36). In the indentationis the guided, axially movable valve member (37) which nay be providedat its outlet end with a slot (38) as recess.

[0116] The embodiments of the device according to the invention forproducing high pressure in a fluid shown in FIGS. 2a to 5 work in thesame way as has already been explained with reference to FIG. 1a.

[0117]FIG. 6a shows a longitudinal section through the preferredatomiser described in detail above with the spring biassed and FIG. 6bshows a longitudinal section through the atomiser with the springreleased.

[0118] The upper housing part (51) contains the pump housing (52) on theend of which is mounted the holder (53) for the atomiser nozzle. Thisholder is preferably a described in German Patent ApplicationP19536303.3-51 of Oct. 4, 1995 (and a parallel PCT application beingfiled simultaneously herewith in the joint names of Boehringer IngelheimInternational GmbH and the inventors) the entire contents of which areincorporated herein by reference. In the holder is the nozzle member(54) and a filter (55). The hollow piston (57) fixed in the cup-shapeddrive flange (56) of the blocking mechanism (57) partly projects intothe cylinder of the pump housing. At its end the hollow piston carriesthe valve member (58). The hollow piston is sealed off by the seal (59).Inside the upper housing part is the annular abutment (opposite annularridge (60) on the flange) on which the flange rests when the spring isreleased. On the axial end of the cup-shaped driven flange is theabutment (61) by which the driven flange is held when the spring isbiased. After the biassing of the spring, the generally annular blockingmember (62) moves between the abutment (61) and a support (63) in theupper housing part, either because of its own elasticity or (when it ismore rigid) by virtue of an external spring (not shown). The actuatingbutton (64) is connected to the blocking member and can either move itbodily or deform it so that it releases the abutment (61). The upperhousing part terminates in the mouth piece (65) and is closed off by theprotective cap (66) which can be fitted thereon.

[0119] The spring housing (67) with compression spring (68) is rotatablymounted on the upper housing part by means of the snapping lug (69) androtary bearing. The lower housing part (70) is pushed over the springhousing and rotates with it to operate the helical sawtooth cam drive(not shown) for cocking the atomiser (moving it from the FIG. 6bposition to the FIG. 6a condition). Inside the spring housing is thereplaceable storage container (71) for the fluid (72) which is to beatomised. The storage container is fitted with a stopper (73) throughwhich the hollow piston projects into the storage container and dips itsend into the fluid.

[0120] Mounted in the outer surface of the spring housing is the spindle(74) for the mechanical counter. At the end of the spindle facing theupper housing part is the drive pinion (75). The slider (76) sits on thespindle.

[0121] The embodiments shown in the drawings may be varied further. Thecomponents may be used together in a manner other than that shown in thedrawings.

EXAMPLE 1

[0122] Miniaturised device for producing high pressure for a medicinalatomiser

[0123] The valve area of a medicinal atomiser according to FIG. 1aconsists of a cylinder made of polybutylene-terephthalate with aninternal diameter of 1.6 mm and an external diameter of 5 mm. The highpressure chamber is closed off by a nozzle carrier plate. In this plateis a nozzle 20 μm in diameter and the nozzle channel is 2 mm long.

[0124] A metal hollow piston with an external diameter of 1.59 mm and abore 0.35 mm in diameter is pushed into the cylinder. The hollow pistoncan be pushed 50 mm into the cylinder and its stroke is 12 mm long. Thehollow piston has an encircling turned groove 4 mm wide with a basediameter of 0.75 mm. The groove is bounded by a 4.0 mm long step with adiameter 1.15 mm. The outer edge of the turned end of the hollow pistonis chamfered.

[0125] The valve member made of polybutyleneterephthalate consists of a2 mm thick disk 1.59 mm in diameter and 3 snap hooks. Threesemi-cylindrical channels 0.4 mm in diameter are provided as recesses onthe outer surface of the disk. The snap hooks project 6 mm from the diskand the inner edge of the hooks is 4.2 mm away from the disk. The valvemember may thus be moved axially 0.2 mm relative to the hollow piston.

[0126] The delivery volume is 23.4 mm³. The pressure in the fluid isabout 32 MPa (320 bar).

[0127] This atomiser is used to atomise or nebulize liquidpharmaceuticals for medicinal aerosol therapy. The atomiser delivers thedrug in the required dose on each actuation.

EXAMPLE 2

[0128] Miniaturised device for producing high pressure for a cosmeticatomiser

[0129] The valve area of a cosmetic atomiser corresponding to FIG. 3aconsists of a cylinder of polyetherether-ketone with an internaldiameter of 2.5 mm and an outer diameter of 8 mm. The high pressurechamber is closed off by a nozzle carrier plate. In this plate is anozzle 25 μm in diameter with a nozzle channel 2 mm long.

[0130] A hollow piston of reinforced plastics with an external diameterof 2.48 mm and a bore 0.5 mm in diameter is pushed into the cylinder.The hollow piston can be pushed 45 mm into the cylinder and its strokeis 24 mm. The hollow piston is drilled out to an internal diameter of1.85 mm over a length of 5.0 mm at its outlet end. The base of thedrilled-out chamber in the hollow piston is chamfered. The outlet end ofthe hollow piston is thermally deformed.

[0131] The valve member is a cylinder of polypropylene which is 3.0 mmhigh and 1.6 mm in diameter. Four stepped channels are provided asrecesses in the outer surface. The valve member can be displaced axiallyabout 0.5 mm inside the hollow piston.

[0132] The delivery volume is about 116 mm³. The pressure in the fluidis about 3 MPa (30 bar).

[0133] This atomiser is used to atomise a hair spray.

1. A device for producing high pressure in a fluid, comprising a pistonwhich is movable in a cylinder, a high pressure chamber which is locatedin front of the piston inside the cylinder, and a valve, which deviceincludes a cylindrical hollow piston, a valve member which is guided bythe hollow piston and is mounted so as to be axially movable against thehollow piston, a stop means on the hollow piston which holds the valvemember to the hollow piston, and a defined seating surface at the inletend of the valve member.
 2. A device according to claim 1, including acylindrical hollow piston with a stop on the outside of the hollowpiston in the region of its outlet end, a cylindrical valve member whichis guided and mounted so as to be axially movable directly at the outletend of the hollow piston, a plurality of undercut snap hooks mounted onthe valve member, and a defined sealing surface at the inlet end of thevalve member on the flat outlet end of the hollow piston.
 3. A deviceaccording to claim 1 or 2, including an encircling, preferably turned orshaped grove or a shaped taper with an encircling, outwardlyfunnel-shaped edge as the stop means at the outlet end of the hollowpiston, the external diameter of the hollow piston at its end beinggreater than the base diameter of the groove or the external diameter ofthe taper and less than the diameter of the cylinder, or severalpreferably two, diametrically opposite points at the outlet end of thehollow piston with flattened surfaces and a step acting as stop means.4. A device according to claim 1, including a hollow piston having aninwardly shaped edge at the outlet end of the hollow piston to act asstop means, a cylindrical valve member which is guided and mounted inaxially movable manner directly in front of the outlet end of the hollowpiston, a coaxial undercut peg on the valve member, and a definedsealing surface which rests on the shaped edge at the outlet end of thehollow piston.
 5. A device according to claim 1, 2 or 4, including acylindrical valve member the diameter of which is less than the internaldiameter of the cylinder or a cylindrical valve member the diameter ofwhich is equal to the internal diameter of the cylinder, and at leastone channel extending in the axial direction of the valve member,preferably on the outer surface of the valve member.
 6. A deviceaccording to claim 1, including a cylindrical hollow piston having awidened portion at one end, the inner diameter of which is greater thanthe inner diameter in the remainder of the hollow piston, an inwardlyshaped edge of the hollow piston, a valve member which is guided andmounted in axially movable manner inside the hollow piston in thewidened portion thereof, the maximum diameter of the valve member beingless than the internal diameter of the hollow piston in its widenedportion and greater than the internal diameter in the remainder of thehollow piston, at least one recess in the region of the outlet end ofthe valve member, a defined sealing surface located inside the hollowpiston at the inlet end of the valve member.
 7. A device according toclaim 6, including a cylindrical hollow piston having a widened portionat the outlet end of the hollow piston, an inwardly shaped edge at theoutlet end of the hollow piston as a stop means, at least one recess inthe valve member at the outlet end thereof, or at least one recess inthe stop means of the hollow piston.
 8. A device according to claim 6,including a cylindrical hollow piston having a widened portion at theinlet end of the hollow piston, an inwardly shaped edge at the inlet endof the hollow piston as a defined sealing surface, a stop means at theoutlet end of the widened portion of the hollow piston, at least onerecess in the valve member at the outlet end thereof, or at least onerecess in the stop means of the hollow piston.
 9. A device according toclaim 1, including a cylindrical hollow piston having an inwardly shapededge at one end of the hollow piston, an encircling constriction nearthe shaped edge of the hollow piston, a valve member which is guided andmounted in axially movable manner inside the hollow piston between theshaped edge and the encircling constriction, the maximum diameter of thevalve member being less than the internal diameter of the hollow piston,a recess in the region of the outlet end of the valve member, a definedsealing surface which is located inside the hollow piston at the inletend of the valve member.
 10. A device according to claim 9, including acylindrical hollow piston having an inwardly shaped edge at the outletend of the hollow piston as a stop means, an encircling constriction inthe region of the shaped edge at the outlet end of the hollow piston, atleast one recess in the valve member at the outlet end thereof, or atleast one recess in the stop means of the hollow piston.
 11. A deviceaccording to claim 9, including a cylindrical hollow piston having aninwardly shaped edge at the inlet end of the hollow piston as a definedsealing surface, an encircling constriction in the vicinity of theshaped edge at the inlet end of the hollow piston as a stop means, atleast one recess in the valve member at the outlet end thereof, or atleast one recess in the stop means of the hollow piston.
 12. A deviceaccording to claim 1, including a cylindrical hollow piston, a fistencircling constriction at a spacing from the outlet end of the hollowpiston as a stop means, a second encircling constriction between thefist constriction and the inlet end of the hollow piston as a definedsealing surface, a valve member which is guided and mounted in axiallymovable manner between the two constrictions.
 13. A device according toclaim 1, 6 or 12, including a preferably cylindrical valve member havingat least one recess in the valve member at the outlet end thereof, or apreferably cylindrical valve member and at least one recess in the stopmeans of the hollow piston.
 14. A device according to clam 1, 9 or 12,including a displacement body having an axially extending channel, whichis arranged in the inlet end of the hollow piston and fixedly connectedto the hollow piston and preferably extends as far as the encirclingconstriction which is closest to the inlet end of the hollow piston, 15.A device according to claim 1, 9 or 12, including a displacement bodyhaving an axially extending channel, which is mounted in the outlet endof the hollow piston and is fixedly connected to the hollow piston andpreferably extends as far as the encircling constriction which isclosest to the outlet end of the hollow piston.
 16. A device accordingto claim 1, including a cylindrical hollow piston having a widenedportion at the entry end and optionally a tube as the displacement bodyin the unwidened part of the hollow piston, a closure member connectedto the widened end of the hollow piston and containing a flat or conicaldepression with a bore, a valve member which is guided and mounted inaxially movable manner in the depression, and which is optionallyprovided at the outlet end with a slot as recess or a notch. a stopmeans in the region of the outlet end of the valve member and a definedsealing surface at the inlet end of the valve member.
 17. An atomiserfor atomising a fluid, comprising an upper housing part, a lower housingpart, a spring housing, a spring, a pump housing, a nozzle, a blockingmechanism and a storage container, the atomiser including a pump housingfixed in the upper housing part and having at one end a nozzle memberwith the nozzle, a hollow piston with a valve member, a drive flange inwhich the hollow piston is secured and which is located in the upperhousing part, a blocking or latching mechanism arranged in the upperhousing part, a spring housing with the spring located therein, which isrotatably mounted on the upper housing part by means of a rotarybearing, a lower housing part which can be fitted onto the springhousing in the axial direction.
 18. An atomiser for atomising a fluid,comprising an upper housing part, a lower housing part, a springhousing, a spring, a pump housing, a nozzle, a blocking mechanism and astorage container, the atomiser including a pump housing fixed in theupper housing part and having at one end a nozzle member with thenozzle, a hollow piston with a valve member according to any one ofclaims 1 to 16, which optionally projects partly into the cylinder ofthe pump housing and is optionally mounted in axially movable manner inthe cylinder. a drive flange in which the hollow piston is secured andwhich is located in the upper housing part, a blocking or latchingmechanism arranged in the upper housing part, a spring housing with thespring located therein, which is rotatably mounted on the upper housingpart by means of a rotary bearing, a lower housing part which can befitted onto the spring housing in the axial direction.
 19. An atomiseraccording to claim 17 or 18, comprising a blocking mechanism in the formof a helical thrust gear, with a blocking member arranged in annularconfiguration with engaging locking surfaces and an actuating button.20. An atomiser according to any one of claims 17 to 19, comprising amechanical counter having a spindle and a slide, which is mounted on thespring housing in the region of the outer surface, and the axis of whichruns parallel to the axis of the spring housing.
 21. An atomiseraccording to any one of claims 17 to 20, comprising a nozzle membercomprising two glass and/or silicon plates firmly joined together, atleast one plate having one or more microstructured channels whichconnect the nozzle inlet end to the nozzle outlet end, and the nozzleoutlet end has at least one opening less than or equal to 10 μm in size(hydraulic diameter).
 22. An atomiser according to claim 21, comprisinga nozzle member having at least two nozzle openings at the outlet end,the directions of spraying being inclined relative to one another andmeeting in the vicinity of the nozzle openings.
 23. An atomiseraccording to any one of claims 17 to 22, comprising a non-return valvemounted in the pump housing between the nozzle opening and high pressurechamber of the cylinder.
 24. An atomiser according to any one of claims17 to 23, comprising a hollow piston which exerts a pressure of 5 to 60MPa (about 50 to 600 bar) on the fluid at its end facing the nozzle(high pressure end) at the moment of actuation of the spring.
 25. Anatomiser according to claim 24, comprising a hollow piston (57) whichexerts a pressure of 10 to 60 MPa (about 100 to 600 bar) on the fluid atits end facing the nozzle (high pressure end) at the moment of actuationof the spring (68).
 26. An atomiser according to any one of claims 17 to25, comprising a replaceable storage container for the fluid arranged inthe lower housing part.
 27. A storage container for a fluid, containinga pharmaceutical composition, for use in an atomiser according to anyone of claims 17 to
 26. 28. Use of the atomiser according to any one ofclaims 17 to 27 for producing medicinal aerosols without propellant gas.29. A storage container according to claim 27, containing apharmaceutically acceptable solution of a medicament selected from thegroup comprising: berotec, berodual, flunisolide, atrovent, salbutamol,budesonide, combivent, tiotropium, oxivent and suitable peptides.
 30. Anatomiser for spraying liquid at high pressure comprising a pump forpressurising a predetermined volume of liquid and discharging it throughan atomising nozzle, the pump comprising a cylinder, a pistonreciprocable therein, the piston being tubular and providing an inletflow path to the cylinder beyond a first end of the piston and beingprovided with a non-return valve, a liquid reservoir having a topsurface, membrane, stopper or cap of resilient material penetrated bythe other end of the piston to permit liquid flow from the reservoirthrough the length of the piston into the cylinder on the inductionstroke, the piston and the reservoir being fixed relative to each otherwhen the pump is operated, and a pump reciprocating means for moving thepiston and cylinder relatively to each other.
 31. An atomiser accordingto claim 30, wherein the second end of the piston is pointed for initialpenetration of the resilient top surface, membrane, stopper or cap ofthe reservoir.
 32. An atomiser according to claim 31, wherein the pumpreciprocating means comprises a spring-loaded flange or other member onthe piston, such that the spring operates the pump in the compressiondirection, and means for tensioning the spring when the pump operates inthe induction direction.
 33. An atomiser according to claim 32, whereinthe means for tensioning comprises a helical saw tooth cam operated byrotating one part of the atomiser relative to another part.
 34. Anatomiser according to claim 32 or 33, wherein the pump reciprocatingmeans comprises a manually operable latch for temporarily holding thespring in its loaded condition prior to discharge of pressurised fluid.35. An atomiser according to any one of claims 30-34 which is adapted topressurise liquid to a pressure of at least 50 bar.
 36. An atomiseraccording to any one of claims 17-26 which is a metered dose inhaler forproducing a mist of liquid medicament for inhalation into the lungs, theliquid droplets having a mass mean size of not more than 12 micrometres.37. A reciprocating pump device for producing high pressure in a fluid,comprising a cylinder, a hollow cylindrical piston which is movable inthe cylinder and provides a path for fluid therethrough, a high pressurechamber which is located in front of the piston inside the cylinder andwhich is supplied with fluid through said path, and an inlet non-returnvalve member in said fluid path which moves with the piston but iscapable of limited guided movement along the piston axis between aclosed position in contact with a valve seat provided by the piston andan open position spaced from the valve seat, the valve member being soshaped and guided that it cannot rotate about an axis transverse to thepiston axis such that a predetermined surface thereof engages the seat.38. A device according to claim 37, wherein the valve member isgenerally cylindrical and is mounted in the hollow piston front end, theeffective area of the valve seat being substantially the same as that ofthe piston bore.
 39. A device according to claim 38, wherein the valveseat is frustoconical.
 40. An atomiser according to any one of claims30-36 incorporating a device according to any one of 37-39.
 41. Anatomiser according to any one of claims 17-26, 30-36 and 40, having anozzle and a filter upstream of the nozzle.